Quantitative Analysis Of Vulnerable Plaque In Carotid Atherosclerotic Patients By MDCT And MRI T2-mapping

The study was divided into two partsPart one Quantitative Analysis of Carotid Atherosclerotic Plaque by MDCTObjective To explore the predictive value of pre-contrast CT value and enhancement amplitude of carotid atherosclerotic plaque for cerebrovascular symptoms.Meterials and Methods 87 patients diagnosed carotid atherosclerosis were included and accepted non-enhanced and enhanced MDCT scan.According to the presence or absence of cerebrovascular symptom, the patients were divided into symptomatic group(n=38) and asymptomatic group(n=49). The CT values were measured on non-enhanced and enhanced CT scan by manually outlining the ROI on non-calcified plaque section, and then the differences between two groups were evaluated using the independent t-test. The ROC curve was used to evaluate the optimal threshold and diagnostic efficacy of pre-contrast CT value and enhancement amplitude in predicting cerebrovascular symptom and the difference of area under ROC curve(AUC) were analyzed using Z test.Results The pre-contrast CT value of symptomatic group and asymptomatic group were(45.58±8.94)HU and(31.09±6.83)HU, respectively, and the difference was statistically significant( t=- 8.569, P<0.001). Enhancement amplitude of the symptomatic group was higher than that in asymptomatic group(t=-3.421, P =0.001).ROC analysis showed that 37.20 HU of pre-contrast CT value was the optimal threshold to predict cerebrovascular symptom, the specificity, sensitivity and accuracy was92.11%(35/38), 81.63%(40/49), 86.21%(75/87), respectively, the AUC was 0.937,while the optimal threshold of enhancement amplitude was 10.1HU, the specificity,sensitivity and accuracy was 76.32%(29/38), 68.97%(60/87), 63.27%(31/49),respectively, the AUC was 0.735. The difference of AUC between two groups was statistically significant(Z=3.613, P<0.01).Conclusion The pre-contrast CT value and enhancement amplitude on part of non-calcified carotid artery plaque have relationship with cerebrovascular symptom.The pre-contrast CT value of plaque superior to enhancement amplitude in evaluating whether caused cerebrovascular symptom.Part two Discussion the Value of MRI T2-mapping Quantitative Assessment Carotid PlaqueObjective To investigate the MRI T2-mapping assessment the value of carotid artery plaque, plaque and quantitative analysis of the relationship between cerebrovascular symptoms.Materials and Methods In order to locate the plaque of carotid artery, 25 patients with carotid atherosclerosis were examined by 3.0T MRI with 3D-TOF and 3D-FSE T1 W scanning. The original images were obtained after T2-mapping(multi-spin echo sequence) scanning. The T2 values ??of plaque in the narrowest lumen were measured on T2 maps after post-processing the original images. According to cerebrovascular symptoms, the patients were divided into two groups, and using independent sample t test to compare the differences of T2 values of plaque in two groups. The ROC curve was used to evaluate the optimal threshold and diagnostic efficacy of T2 value in predicting cerebrovascular symptom.Results The T2 values of ??carotid artery plaque in symptomatic and asymptomatic were(111.43 ± 46.54) ms and(59.25 ± 39.77) ms, respectively. And the difference of T2 values was statistically significant(t =-3.421, P <0.01). ROC analysis showed that65.38 ms of T2 values was the optimal threshold to predict cerebrovascular symptom,the specificity, sensitivity and accuracy were 94.1%(16/17), 93.3%(14/15), 93.8%(30/ 32), respectively.Conclusion MRI T2-mapping technique can quantitatively assess carotid plaque components. T2 values of carotid plaques are associated with cerebrovascular symptom.The T2 value of symptomatic plaque group was significantly higher than the asymptomatic group.